An electrolyte solution including a solvent, the solvent containing a compound (1a) represented by the following formula (1a); and

##STR00001##

a compound (2) represented by the following formula (2):

##STR00002##

wherein R.sup.e is a C1-C5 linear or branched alkyl group optionally containing an ether bond; R.sup.f is a C1-C5 linear or branched alkyl group optionally containing an ether bond; and at least one of R.sup.e or R.sup.f contains a fluorine atom. Also disclosed is an electrochemical device including the electrolyte solution, a lithium-ion secondary battery including the electrolyte solution, and a module including the electrochemical device or the lithium-ion secondary battery.

Electrolytes and electrolyte additives for use in energy storage devices, comprising cyclic carbonate compounds.

An electrolyte including a dinitrile compound, a trinitrile compound, and propyl propionate. Based on the total weight of the electrolyte, the weight percentage of the dinitrile compound is X, the weight percentage of the trinitrile compound is Y, and the weight percentage of the propyl propionate is Z, wherein about 2.2 wt %≤(X+Y)≤about 8 wt %, about 0.1≤(X/Y)≤about 6, 1 wt %≤Y<5 wt %, about 5 wt %≤Z≤about 50 wt %, and about 0.02<(Y/Z)≤about 0.3. The electrolyte further includes at least one selected from the group consisting of a cyclic carbonate ester having a carbon-carbon double bond, a fluorinated chain carbonate ester, a fluorinated cyclic carbonate ester, and a compound having a sulfur-oxygen double bond.

Provided are an electrolytic solution suitable for a lithium ion secondary battery that includes a positive electrode which has a positive electrode active material having an olivine structure, and includes a negative electrode having graphite as a negative electrode active material, and a superior lithium ion secondary battery having the electrolytic solution. The lithium ion secondary battery includes: a positive electrode that includes a positive electrode active material having an olivine structure; a negative electrode having graphite as a negative electrode active material; and an electrolytic solution. The electrolytic solution contains LiPF.sub.6, a cyclic alkylene carbonate selected from ethylene carbonate and propylene carbonate, methyl propionate, and an additive that starts reductive degradation at a potential higher than a potential at which the above components of the electrolytic solution start reductive degradation.

A non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery including the same are disclosed herein. In some embodiments, a non-aqueous electrolyte includes a lithium salt, a non-aqueous solvent, a compound represented by Formula 1, and a compound represented by Formula 2, wherein the compound represented by Formula 1 and the compound represented by Formula 2 are included in a volume ratio of 1:0.1 to 1:1.5. Also, a lithium secondary battery including the non-aqueous electrolyte has improved high-temperature storage safety.

Electrolytes and electrolyte additives for energy storage devices comprising phosphazene based compounds are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte comprising at least two electrolyte co-solvents, wherein at least one electrolyte co-solvent comprises a phosphazene based compound.

The present application provides an electrolyte, the electrolyte including a fluorinated metal salt with S═O or P═O; and a titanate with a structural formula Ti—(O—R.sub.1).sub.4, where the R1 is selected from one or more of C.sub.1-C.sub.6 alkyl, C.sub.1-C.sub.6 halogenated alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl or C.sub.1-C.sub.6 silyl, and a secondary battery including the electrolyte, a battery module, a battery pack and a power consumption apparatus.

An aspect of the present invention is a nonaqueous electrolyte energy storage device including a negative electrode containing metal lithium, a nonaqueous electrolyte including a fluorinated solvent, and a separator with an air permeability resistance of 150 seconds or less.

An object is to provide a nonaqueous electrolyte and a nonaqueous-electrolyte secondary battery which have excellent discharge load characteristics and are excellent in high-temperature storability, cycle characteristics, high capacity, continuous-charge characteristics, storability, gas evolution inhibition during continuous charge, high-current-density charge/discharge characteristics, discharge load characteristics, etc. The object has been accomplished with a nonaqueous electrolyte which comprises: a monofluorophosphate and/or a difluorophosphate; and further a compound having a specific chemical structure or specific properties.

Disclosed herein are electrolyte compositions comprising a fluorinated solvent, at least one silyl oxalate represented by the formulas RR′Si(C.sub.2O.sub.4), wherein R and R′ are each the same or different from each other and independently selected from C.sub.1-C.sub.8 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.2-C.sub.8 alkynyl, or C.sub.6-C.sub.10 aryl radical, optionally comprising at least one substituent selected from halogen, hydroxyl, alkoxy, carbonyl, and carboxyl groups; and LiPF6. Also disclosed herein are electrolyte compositions comprising a fluorinated solvent and a lithium oxalato phosphate salt represented by the formula LiPF.sub.(6-2q)(C.sub.2O.sub.4).sub.q, wherein q is 1, 2 or 3; wherein the oxalato phosphate salt comprises at least a portion that is derived from at least one silyl oxalate as defined herein. The electrolyte compositions are useful in electrochemical cells, such as lithium ion batteries.